Not true, they just use a bracket to combine the regular batteries. i have recently replaced batteries of my BR1000G-IN and external battery pack. 2 for the main ups and 4 for the external pack. 12v 9a each. easiest upgrade.APC mostly use proprietary battery - hence replacement has to done through them. I mostly prefer UPS which have the regular 12v 7ah batteries - which are easily available in markets and so when the time comes to replace the battery - you can do it on your own